1. Field of Invention
This invention relates to a holder for a tool and, in particular, to a holder for a key used for the attachment of aerospace fasteners.
2. Brief Statement of the Prior Art
A particular fastening system has been developed for use in the aerospace industry, which employs frangible fasteners comprising a bolt with a nut member having a threaded collar and a wrenching ring separated by a notched section that provides a predetermined limiting torque which when exceeded, permits the wrenching ring to shear from the threaded collar, leaving the latter in place at a precise and predetermined tensile loading on the bolt. Often, the threaded collar has an upset portion usually a slightly elliptical shape to provide a frictional spring lock to prevent the fastener from spinning off the bolt in the event that the residual tension on the fastener is lost.
The threaded fasteners are used both in loose and interference fit applications. In loose fit applications in it is difficult to work from both sides of the workpiece, and it has been the practice to use a drive tool to apply the fasteners which has a center key that is inserted into a broached keyway in the end of the bolt to hold the bolt stationary while the threaded collar is applied.
In my prior, parent application, Ser. No. 514,783, now U.S. Pat. No. 4,538,483, I disclose an improved wrenching tool in which a key member is provided with a distal groove and is received in a key holder which has a detent ball that is mounted in a lateral bore and that engages the distal groove of the key member. The key holder is slidably received in a central bore of the rotationally driven socket member which has an interior ball cavity. The precise alignment of the ball cavity in the socket member with the lateral groove of the key holder permits the detent ball to move outwardly, releasing the key and permitting its removal. In my prior application, Ser. No. 823,009, now U.S. Pat. No. 4,721,022, I disclose a release mechanism in the drive tool which precisely locates the detent ball for release of the key.
Keys can become jammed in the keyway of the drive tool, particularly when the end of the key is sheared off during use of the tool. In my aforementioned '844 patent, I disclose that the keyway in the center of the holder can be intersected by a bore drilled at an angle from one side of the holder so that one can insert a pin or other tool to clear the keyway of any jammed portion of a key.
It is difficult to drill a bore at an angle into the holder so that it intersects the tool receptacle or keyway at the necessary location for forcing the ejection of a jammed key. Additionally, this approach requires the use of a relatively slender and, itself, a fragile pin for ejection of the jammed key.